Electrophoresis sample applicator

ABSTRACT

This invention provides an apparatus and applicator for applying liquid sample to an electrophoretic membrane. The applicator comprises two parallel strips of flexible plastic film separated by a spacer along one edge. At the other edge the strips form fingers between which are suspended liquid samples. The applicator is gripped at the laminated edge by the apparatus at the end of an arm pivotally mounted on a base plate. The arm is connected by mechanical linkage to a handle which controls movement of the arm such that the applicator can be lowered to contact a membrane supported by the base plate with the correct amount of force to deposit the liquid samples cleanly and precisely on the membrane. The gripping element of the apparatus can be adjusted to control the spacing between the fingers and thereby control the amount of sample deposited.

United States Patent 1 Klein et al.

1 1 Oct. 1, 1974 1 i ELECTROPHORESIS SAMPLE APPLICATOR [75] Inventors:Gerald Lee Klein, Orange; Richard Carl Meyer, La Habra, both of Calif.

[73] Assignee: Beckman Instruments, Inc.,

Fullerton, Calif.

[22 Filed: June 15,1973

[21] Appl. No.: 370,348

[52] U.S. Cl. 204/299, 204/180 0, 204/180 5 [51] Int. Cl B01k 5/00 [58]Field. of Search 204/180 G, 180 S, 299

[56] References Cited UNITED STATES PATENTS 3,317,418 5/1967 Zec 204/2993,428,547 2/1969 Zec 204/299 3,616,387 10/1971 Siebert et al 204/180 GOTHER PUBLICATIONS Houtsmuller, A Simple Device for Applying Serum toViscous Media, Clin. Chim. Acta., 10, (1964), pp. 94 & 95.l-Ioutsmuller, "Agarose-Gel-EIectrophoresis of. Lipoproteins, Charles C.Thomas publisher, 1969, pp. 13-15.

Primary Examiner.l0hn H. Mack Assistant ExaminerA. C. Prescott Attorney,Agent, or FirmR. .I. Steinmeyer; J. G. Mesaros 5 7] ABSTRACT Thisinvention provides an apparatus and applicator for applying liquidsample to an electrophoretic membrane. The applicator comprises twoparallel strips of flexible plastic film separated by a spacer along oneedge. At the other edge the strips form fingers between which aresuspended liquid samples. The appli cator is gripped at the laminatededge by the apparatus at the end of an arm pivotally mounted on a baseplate. The arm is connected by mechanical linkage to a handle whichcontrols movement of the arm such that the applicator can be lowered tocontact a membrane supported by the base plate with the correct amountof force to deposit the liquid samples cleanly and precisely on themembrane. The gripping element of the apparatus can be adjusted tocontrol the spacing between the fingers and thereby control the amountof sample deposited.

14 Claims, 4 Drawing Figures PAIENIED sumaer 4 FIG. 2

1 ELECTROPHORESIS SAMPLE APPLICATOR BACKGROUND OF THE INVENTION Certainanalytical procedures, such as electrophoresis, require the depositingof precise amounts of liquid sample, such as serum, at precise places ona gel or membrane resting on a carrier plate or slide. In the case of agel, the sample is usually deposited manually, such as by pipetting thesample into preformed cavities or by applying the sample with a spatula(as described in US. Pat. No. 3,622,484) or other hand-held device. Ineither event, the operation is tedious, time consuming, requires manualskill, and is subject to operator error, with the result that frequentlyeither too much or too little sample is deposited, or the sample issmeared or splattered on the gel or membrane. It is an object of thisinvention to provide an improved method, apparatus and applicator forapplying liquid sample to a gel or membrane.

SUMMARY OF THE INVENTION This invention provides an apparatus andapplicator for applying liquid sample, such as blood serum, to amembrane, such as an agarose gel electrophoretic membrane. Theapplicator is gripped by the apparatus at the end of an arm pivotallymounted on a base plate. The arm is mechanically connected to a handlesuch that rotation of the handle results in rotation of the arm,whereby, when a membrane is placed on the base plate, rotation of thehandle causes the applicator to contact the membrane and release samplecontained by the applicator. In a preferred embodiment, the means forgripping the applicator includes means for adjusting the horizontalalignment of the applicator and means for adjusting the sample holdingcapacity of the applicator. The applicator comprises two strips offlexible film separated at one edge by a spacer laminated between thestrips, with each strip having a plurality of fingers at the oppositeedge which define capillary spaces between the strips for containingliquid sample. The apparatus and applicator of the invention overcomethe problems inherent in the prior art methods of applying samplemanually.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of the apparatusof this invention showing the arm in a slightly raised position with theapplicator gripped at the end of the arm.

FIG. 2 is an exploded view of the apparatus of this invention.

FIG. 3 is a front view of an applicator used with the apparatus.

FIG. 4 is a side view of the applicator.

DETAILED DESCRIPTION The apparatus comprises an arm pivotally mountedbetween two support blocks 11 secured to a base plate 12 by screws 13.The arm 10 pivots on bushings 14 about pins 15. Also pivotally mountedbetween the support blocks 11 is a handle 16, which pivots on bushings17 about pins 18. The handle 16 is connected to the arm 10 through alink 19. The link 19 is secured to the handle 16 by pin 20 and to thearm 10 by pin 21 at places offset from the axes of rotation such that asthe arm 10 approaches a horizontal position, a large angular movement ofthe handle 16 results in a cone spondingly smaller angular movement ofthe arm 10.

This ensures that the applicator enters and leaves the gel in aslow,deliberate motion so that even an untrained operator can make a preciseapplication of sample each time.

One end of the arm 10 terminates in a face 22. A jaw 23 contacts theface 22 and is held in place by an adjusting knob 24 which threadedlyengages a screw 25 passing through the face 22. The knob 24 has aspherical base which engages a spherical depression in the jaw 23. Thelower edge of the jaw 23 forms a lip 26. A spring 27 biases the upperportion of the jaw 23 away from the face 22. A fin extending from thejaw 23 engages a slot 28 in the face 22 and thereby limits therotational freedom of the jaw 23. However, the jaw 23 is free to rotatein a plane perpendicular to the surface of the face 22 about an axispassing through the knob 24.

The applicator comprises two strips 40 of flexible film, such as plastic(e.g., polyester) film, separated at the top by a spacer 41 laminatedbetween the strips. The inner surfaces of the strips are preferablycoated with a hydrophilic material, such as gelatin. The outer surfacesare preferably hydrophobic. Each strip 40 has a plurality of fingers 42which define capillary spaces between the strips for containing theliquid samples, which are released when the fingers contact the gel. Thefingers of one strip are preferably slightly longer than the fingers ofthe other strip so that the fingers cut and enter the gel cleanly. Ifthe fingers were the same length, they would tend to crush the gelrather than pierce it. The shorter fingers preferably have holes 43 inthem to facilitate loading of sample.

The applicator is positioned between the jaw 23 and the face 22 bypushing the upper portion ofjaw 23 toward the face 22 to move the lip 26away from the face, and then inserting the applicator such that a notch44 in the top of the applicator engages a protrusion 29 on the face 22,followed by releasing the upper portion of jaw 23 to secure theapplicator between the lip 26 and the face 22. The protrusion 29 fixesthe lateral position of the applicator while permitting it to rotate sothat it can be aligned horizontally.

The applicator is aligned horizontally by lowering the arm 10 until thetips of the fingers 42 touch a slide (not shown) resting on the baseplate 12. As the fingers 42 touch the slide, the grip on the applicatoris relaxed briefly by squeezing the upper portion of the jaw 23 towardthe face 22, which permits the tips of the fingers to align horizontallyon the surface of the slide.

After the fingers 42 have been aligned, the spacing between the stripsmay be adjusted to control the amount of sample contained between thefingers. The spacing is adjusted by rotating the adjusting knob 24. Whenthe knob 24 is rotated completely in one direction, the surface of thejaw 23 is parallel to the surface of the face 22. The strips 40 of theapplicator are then parallel and the space between them is equal to thethickness of the spacer 41. When the knob 24 is rotated in the otherdirection, the jaw 23 becomes angular with respect to the face 22. Sincethe front fingers rest against the lip 26 of the jaw 23, while the backfingers rest against the surface of the face 22, as the jaw becomesangular the front fingers become bent toward the back fingers. Thus, thelower edges of the strips 40 may be made closer or farther apartdepending on the setting of the knob 24, with the result that arepeatable amount of sample can be deposited in the gel with a minimumof operator skill.

After the fingers 42 have been aligned and the space between themadjusted, liquid sample is introduced into the space between the fingersof the adjacent strips. A particularly convenient method of introducingsample is to dip the fingers into a trough divided into compartmentscorresponding to the fingers. Each compartment contains a separatesample for each pair of fingers. The trough is placed on the base plate12 and the arm is lowered so that each finger enters its respectivecompartment of the trough. The samples flow into the spaces between thefingers by capillary action. Alternatively, sample may be introducedinto the spaces by using a pipette.

The samples are deposited into a gel by placing the membrane on a slideresting on the base plate 12, and lowering the arm 10 by rotating thehandle 16 until the fingers 42 contact the gel. As the fingers contactthe gel, the sample is released.

The base plate 12 has two keypins for accurately positioning the slideby engaging holes in the bottom of the slide. As a result, the samplesare automatically deposited precisely where desired in the gel. Slideswith different keyhole patterns can be used for various applicationrequirements. The keypins can also be used to position the sampletrough.

The applicator illustrated herein is especially suitable for zoneelectrophoresis. However, other applicators,

- such as for immunoelectrophoresis. can also be employed in accordancewith this invention. The jaw and face of the apparatus can, of course,be modified as necessary to accommodate other applicators. Similarly,the apparatus of this invention can be used to apply samples inapplications other than electrophoresis. such as paper chromatography.

What is claimed is:

1. Apparatus for applying liquid sample to a membrane. comprising a baseplate,

an arm pivotally mounted on one end and supported by the base plate.

means at the other end of the arm for gripping a sample applicator.

a handle connected by a mechanical linkage to the arm such that rotationof the handle results in rotation of the arm. whereby. when a membraneis placed on the base plate. rotation of the handle causes theapplicator to contact the membrane and release sample contained by theapplicator.

2. The apparatus of claim 1 wherein the gripping means includes meansfor adjusting the horizontal alignment of the applicator.

3. The apparatus of claim 1 wherein the gripping means includes meansfor adjusting the sample holding capacity of the applicator.

4. The apparatus of claim 1 wherein the mechanical connection betweenthe handle and the arm is such that a large rotation of the handleresults in a correspondingly smaller rotation of the arm as the armapproaches a horizontal position.

I 5. The apparatus of claim 1 wherein the base plate includes keypinsfor accurately positioning the membrane.

6. The apparatus of claim 1 wherein the gripping means comprises a faceat the end of the arm,

an adjusting knob threadedly engaged to the face,

a jaw between the face and the knob, the jaw being free to rotate in aplane perpendicular to the surface of the face about an axis passingthrough the adjusting knob.

means biasing the upper portion of the jaw away from the face.

7. The apparatus of claim 6 wherein the face includes a protrusion forfixing the lateral position of the applicator.

8. The apparatus of claim 1 in combination with a sample applicatorcomprising two substantially parallel strips of flexible film separatedat one edge by a spacer laminated between the strips, each strip havinga plurality of fingers at the opposite edge which define capillaryspaces between the strips for containing liquid sample.

9. The combination of claim 8 wherein the. applicator has a notch at thelaminated edge for engaging a protrusion in the gripping means forfixing lateral motion of the applicator.

10. A sample applicator comprising two substantially parallel strips ofa flexible film separated at one edge by a spacer laminated between thestrips, each strip having a plurality of fingers at the opposite edgewhich define capillary spaces between the strips for containing liquidsample.

11. The applicator of claim 10 wherein the fingers of one strip areslightly longer than the fingers of the other strip.

12. The applicator of claim 11 wherein each shorter finger has a hole init to facilitate loading of sample.

13. The applicator of claim 12 wherein the inner surfaces of the stripsare hydrophilic.

14. The applicator of claim 13 having a notch at the laminated edgeadapted to engage a protrusion for fixing lateral motion of theapplicator.

l l l

1. Apparatus for applying liquid sample to a membrane, comprising a baseplate, an arm pivotally mounted on one end and supported by the baseplate, means at the other end of the arm for gripping a sampleapplicator, a handle connected by a mechanical linkage to the arm suchthat rotation of the handle results in rotation of the arm, whereby,when a membrane is placed on the base plate, rotation of the handlecauses the applicator to contact the membrane and release samplecontained by the applicator.
 2. The apparatus of claim 1 wherein thegripping means includes means for adjusting the horizontal alignment ofthe applicator.
 3. The apparatus of claim 1 wherein the gripping meansincludes means for adjusting the sample holding capacity of theapplicator.
 4. The apparatus of claim 1 wherein the mechanicalconnection between the handle and the arm is such that a large rotationof the handle results in a correspondingly smaller rotation of the armas the arm approaches a horizontal position.
 5. The apparatus of claim 1wherein the base plate includes keypins for accurately positioning themembrane.
 6. The apparatus of claim 1 wherein the gripping meanscomprises a face at the end of the arm, an adjusting knob threadedlyengaged to the face, a jaw between the face and the knob, the jaw beingfree to rotate in a plane perpendicular to the surface of the face aboutan axis passing through the adjusting knob, means biasing the upperportion of the jaw away from the face.
 7. The apparatus of claim 6wherein the face includes a protrusion for fixing the lateral positionof the applicator.
 8. The apparatus of claim 1 in combination with asample applicator comprising two substantially parallel strips offlexible film separated at one edge by a spacer laminated between thestrips, each strIp having a plurality of fingers at the opposite edgewhich define capillary spaces between the strips for containing liquidsample.
 9. The combination of claim 8 wherein the applicator has a notchat the laminated edge for engaging a protrusion in the gripping meansfor fixing lateral motion of the applicator.
 10. A sample applicatorcomprising two substantially parallel strips of a flexible filmseparated at one edge by a spacer laminated between the strips, eachstrip having a plurality of fingers at the opposite edge which definecapillary spaces between the strips for containing liquid sample. 11.The applicator of claim 10 wherein the fingers of one strip are slightlylonger than the fingers of the other strip.
 12. The applicator of claim11 wherein each shorter finger has a hole in it to facilitate loading ofsample.
 13. The applicator of claim 12 wherein the inner surfaces of thestrips are hydrophilic.
 14. The applicator of claim 13 having a notch atthe laminated edge adapted to engage a protrusion for fixing lateralmotion of the applicator.